https://doi.org/10.1140/epjb/e2005-00307-0
Theory of collective opinion shifts: from smooth trends to abrupt swings
1
E.S.P.C.I, 10 rue Vauquelin, 75005 Paris, France
2
Service de Physique de l'État Condensé,
Orme des Merisiers,
CEA Saclay, 91191 Gif sur Yvette Cedex, France and
Science & Finance, Capital Fund Management, 6-8 Bd
Haussmann, 75009 Paris, France
Corresponding author: a bouchau@spec.saclay.cea.fr
Received:
26
April
2005
Published online:
21
September
2005
We unveil collective effects induced by imitation and social pressure by
analyzing data from three different sources:
birth rates, sales of cell phones and the drop of applause in concert halls. We interpret
our results within the framework of the
Random Field Ising Model, which is a threshold model for collective
decisions
accounting both for agent heterogeneity and social imitation. Changes of
opinion can occur either abruptly or
continuously, depending on the importance of herding effects. The main
prediction
of the model is a scaling relation between the height h of the speed
of variation peak and its width w of the form
, with
for well connected
populations. Our three sets of data are compatible
with such a prediction, with
for birth rates,
for cell phones
and
for clapping. In this last case, we in fact
observe that some clapping
samples end discontinuously (w=0), as predicted by the model for
strong enough imitation.
PACS: 02.50.-r – Probability theory, stochastic processes, and statistics / 87.23.-n – Ecology and evolution / 89.65.-s – Social and economic systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005